1====================== 2Kernel driver i2c-i801 3====================== 4 5 6Supported adapters: 7 * Intel 82801AA and 82801AB (ICH and ICH0 - part of the 8 '810' and '810E' chipsets) 9 * Intel 82801BA (ICH2 - part of the '815E' chipset) 10 * Intel 82801CA/CAM (ICH3) 11 * Intel 82801DB (ICH4) (HW PEC supported) 12 * Intel 82801EB/ER (ICH5) (HW PEC supported) 13 * Intel 6300ESB 14 * Intel 82801FB/FR/FW/FRW (ICH6) 15 * Intel 82801G (ICH7) 16 * Intel 631xESB/632xESB (ESB2) 17 * Intel 82801H (ICH8) 18 * Intel 82801I (ICH9) 19 * Intel EP80579 (Tolapai) 20 * Intel 82801JI (ICH10) 21 * Intel 5/3400 Series (PCH) 22 * Intel 6 Series (PCH) 23 * Intel Patsburg (PCH) 24 * Intel DH89xxCC (PCH) 25 * Intel Panther Point (PCH) 26 * Intel Lynx Point (PCH) 27 * Intel Avoton (SOC) 28 * Intel Wellsburg (PCH) 29 * Intel Coleto Creek (PCH) 30 * Intel Wildcat Point (PCH) 31 * Intel BayTrail (SOC) 32 * Intel Braswell (SOC) 33 * Intel Sunrise Point (PCH) 34 * Intel Kaby Lake (PCH) 35 * Intel DNV (SOC) 36 * Intel Broxton (SOC) 37 * Intel Lewisburg (PCH) 38 * Intel Gemini Lake (SOC) 39 * Intel Cannon Lake (PCH) 40 * Intel Cedar Fork (PCH) 41 * Intel Ice Lake (PCH) 42 * Intel Comet Lake (PCH) 43 * Intel Elkhart Lake (PCH) 44 * Intel Tiger Lake (PCH) 45 46 Datasheets: Publicly available at the Intel website 47 48On Intel Patsburg and later chipsets, both the normal host SMBus controller 49and the additional 'Integrated Device Function' controllers are supported. 50 51Authors: 52 - Mark Studebaker <mdsxyz123@yahoo.com> 53 - Jean Delvare <jdelvare@suse.de> 54 55 56Module Parameters 57----------------- 58 59* disable_features (bit vector) 60 61Disable selected features normally supported by the device. This makes it 62possible to work around possible driver or hardware bugs if the feature in 63question doesn't work as intended for whatever reason. Bit values: 64 65 ==== ========================================= 66 0x01 disable SMBus PEC 67 0x02 disable the block buffer 68 0x08 disable the I2C block read functionality 69 0x10 don't use interrupts 70 0x20 disable SMBus Host Notify 71 ==== ========================================= 72 73 74Description 75----------- 76 77The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 78ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 79Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 80Pentium-based PCs, '815E' chipset, and others. 81 82The ICH chips contain at least SEVEN separate PCI functions in TWO logical 83PCI devices. An output of lspci will show something similar to the 84following:: 85 86 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 87 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 88 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 89 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 90 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 91 92The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 93Controller. 94 95The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 96SMBus controller. 97 98 99Process Call Support 100-------------------- 101 102Block process call is supported on the 82801EB (ICH5) and later chips. 103 104 105I2C Block Read Support 106---------------------- 107 108I2C block read is supported on the 82801EB (ICH5) and later chips. 109 110 111SMBus 2.0 Support 112----------------- 113 114The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 115 116 117Interrupt Support 118----------------- 119 120PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 121 122 123Hidden ICH SMBus 124---------------- 125 126If your system has an Intel ICH south bridge, but you do NOT see the 127SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 128BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 129well known for first doing this on their P4B motherboard, and many other 130boards after that. Some vendor machines are affected as well. 131 132The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 133SMBus was hidden on purpose because it'll be driven by ACPI. If the 134i2c-scmi driver works for you, just forget about the i2c-i801 driver and 135don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 136better make sure that the SMBus isn't used by the ACPI code. Try loading 137the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 138find a thermal zone with type "acpitz", it's likely that the ACPI is 139accessing the SMBus and it's safer not to unhide it. Only once you are 140certain that ACPI isn't using the SMBus, you can attempt to unhide it. 141 142In order to unhide the SMBus, we need to change the value of a PCI 143register before the kernel enumerates the PCI devices. This is done in 144drivers/pci/quirks.c, where all affected boards must be listed (see 145function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 146and you think there's something interesting on the SMBus (e.g. a 147hardware monitoring chip), you need to add your board to the list. 148 149The motherboard is identified using the subvendor and subdevice IDs of the 150host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 151 152 00:00.0 Class 0600: 8086:2570 (rev 02) 153 Subsystem: 1043:80f2 154 Flags: bus master, fast devsel, latency 0 155 Memory at fc000000 (32-bit, prefetchable) [size=32M] 156 Capabilities: [e4] #09 [2106] 157 Capabilities: [a0] AGP version 3.0 158 159Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 160(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 161names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 162and then add a case for your subdevice ID at the right place in 163drivers/pci/quirks.c. Then please give it very good testing, to make sure 164that the unhidden SMBus doesn't conflict with e.g. ACPI. 165 166If it works, proves useful (i.e. there are usable chips on the SMBus) 167and seems safe, please submit a patch for inclusion into the kernel. 168 169Note: There's a useful script in lm_sensors 2.10.2 and later, named 170unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 171temporarily unhide the SMBus without having to patch and recompile your 172kernel. It's very convenient if you just want to check if there's 173anything interesting on your hidden ICH SMBus. 174 175 176---------------------------------------------------------------------------- 177 178The lm_sensors project gratefully acknowledges the support of Texas 179Instruments in the initial development of this driver. 180 181The lm_sensors project gratefully acknowledges the support of Intel in the 182development of SMBus 2.0 / ICH4 features of this driver. 183